Organic EL display

ABSTRACT

An organic EL display includes plural pixels, each including a drive control element, an organic EL element and an output control switch. The drive control element includes a control terminal, a first terminal connected to a first power supply terminal, and a second terminal outputting a current with a magnitude corresponding to a voltage between the control terminal and the first terminal. The organic EL element includes a first electrode, a second electrode connected to a second power supply terminal, and an active layer interposed between the first and second electrodes. The output control switch is connected between the second terminal and the first electrode. In a part of the pixels, a conductive path electrically connecting the first electrode to the first power supply terminal is broken at a portion which connects the output control switch to the first electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. Ser. No. 11/555,302 filed Nov. 1, 2006,which is a Continuation Application of PCT Application No.PCT/JP2005/023197 filed Dec. 13, 2005, which was published under PCTArticle 21(2) in Japanese which claims the benefit of priority under 35U.S.C. §119 from Japanese Patent Application No. 2005-053424 filed Feb.28, 2005, the entire contents of each of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display.

2. Description of the Related Art

In an organic electroluminescent (EL) display, image qualitydeterioration such as luminance unevenness occurs if a drive currentvaries. Therefore, when an active matrix driving method is used in thisdisplay, the characteristics of a drive control element for controllingthe magnitude of the drive current must be substantially the samebetween pixels. In this display, however, the drive control element isnormally formed on an insulator such as a glass substrate, so thecharacteristics of the element easily vary.

U.S. Pat. No. 6,373,454 describes an organic EL display using a currentmirror circuit in a pixel. This pixel includes an n-channel field-effecttransistor (FET) as the drive control element, an organic EL element, acapacitor, an output control switch, a video signal supply controlswitch, and a diode-connecting switch.

The source of the drive control element is connected to a first powersupply line at a low electric potential, and the capacitor is connectedbetween the gate of the drive control element and the first power supplyline. The output control switch is connected between the drain of thedrive control element and the cathode of the organic EL element, and theanode of the organic EL element is connected to a second power supplyline at a higher electric potential. The video signal supply controlswitch is connected between the drain of the drive control element and avideo signal line, and the diode-connecting switch is connected betweenthe drain and gate of the drive control element.

During a write period, the pixel including the current mirror circuit issupplied with a current signal I_(sig) as a video signal. During a holdperiod following the write period, a drive current having a magnitudesubstantially equal to that of the electric current I_(sig) flowsbetween the drain and source of the drive control element. This makes itpossible to eliminate the influence of not only a threshold value V_(th)but also the mobility, dimensions, and the like of the drive controlelement on the drive current.

In an active matrix display, some pixels are sometimes viewed asluminous dots or dark dots owing to disconnections or short circuits inthe pixel circuit. Also, in an active matrix display, pixel columns orrows are sometimes viewed as luminous lines or dark lines owing todisconnections of scan signal lines or video signal lines.

When achieving the present invention, the present inventor has foundthat in an active matrix display in which a current signal is written asa video signal in a pixel circuit, a luminous dot with a luminous ordark line-like tail forms in an image in addition to the line- ordot-like luminance unevenness described above.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to prevent the formation of aluminous dot with a luminous or dark line-like tail in an image on anactive matrix display in which a current signal is written as a videosignal in a pixel circuit.

According to an aspect of the present invention, there is provided anorganic EL display comprising, pixels, each of the pixels comprising adrive control element which includes a control terminal, a firstterminal connected to a first power supply terminal, and a secondterminal outputting a current with a magnitude corresponding to avoltage between the control terminal and the first terminal, an organicEL element which includes a first electrode, a second electrodeconnected to a second power supply terminal, and an active layerinterposed between the first and second electrodes, and an outputcontrol switch which is connected between the second terminal and thefirst electrode, wherein in a part of the pixels, a first conductivepath electrically connecting the first electrode to the first powersupply terminal is broken at a portion which connects the output controlswitch to the first electrode.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a plan view schematically showing a display according to anembodiment of the present invention;

FIG. 2 is a sectional view schematically showing an example of astructure usable as the display shown in FIG. 1;

FIG. 3 is a plan view schematically showing an example of a structureusable as a pixel of the display shown in FIG. 1;

FIG. 4 is a plan view schematically showing a structure after the pixelshown in FIG. 3 is repaired;

FIG. 5 is an equivalent circuit diagram of a pixel included in a displayaccording to a modification;

FIG. 6 is a plan view schematically showing an example of a structureusable as the pixel of the display according to the modification;

FIG. 7 is a plan view schematically showing an example of a structureafter the pixel shown in FIG. 6 is repaired; and

FIG. 8 is a plan view schematically showing another example of thestructure after the pixel shown in FIG. 6 is repaired.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings. Note that the samereference numerals in the drawings denote constituent elements whichachieve the same or similar functions, and a repetitive explanationthereof will be omitted.

FIG. 1 is a plan view schematically showing a display according to anembodiment of the present invention. FIG. 2 is a sectional viewschematically showing an example of a structure usable as the displayshown in FIG. 1. FIG. 3 is a plan view schematically showing an exampleof a structure usable as a pixel of the display shown in FIG. 1. Notethat in FIG. 2, the display is drawn such that the display surface,i.e., the front surface or light-emitting surface faces downwardly, andthe back surface faces upwardly. Note also that FIG. 3 illustrates thestructure of the pixel viewed from the display surface side.

This display is a bottom emission organic EL display using an activematrix driving method. The display includes an insulating substrate SUBsuch as a glass substrate.

On the substrate SUB, as shown in FIG. 2, an SiN_(x) layer and SiO_(x)layer, for example, are sequentially stacked as an undercoat layer UC.

On the undercoat layer UC, semiconductor layers SC such as polysiliconlayers in each of which a channel, source and drain are formed, a gateinsulator GI formed by using, e.g., tetraethyl orthosilicate (TEOS), andgates G made of, e.g., MoW are sequentially stacked to form top-gatetype TFTs. In this embodiment, these TFTs are p-channel TFTs and used asa drive control element DR and switches SW1 to SW3 included in eachpixel PX shown in FIGS. 1 to 3.

On the gate insulator GI, scan signal lines SL1 and SL2 shown in FIG. 1and electrodes E1 shown in FIGS. 1 to 3 are further formed. The scansignal lines SL1 and SL2 and the electrodes E1 can be formed in the samestep as the gates G.

As shown in FIG. 1, the scan signal lines SL1 and SL2 run in the rowdirection (X direction) of the pixels PX, and are alternately arrangedin the column direction (Y direction) of the pixels PX. The scan signallines SL1 and SL2 are connected to a scan signal line driver YDR.

The electrodes E1 are connected to the gates G of the drive controlelements DR. Each electrode E1 is used as one electrode of a capacitor C(to be described later).

The gate insulator GI, gates G, scan signal lines SL1 and SL2, andelectrodes E1 are covered with an interlayer dielectric film II shown inFIG. 2. The interlayer dielectric film II is made of, e.g., an SiO_(x)film formed by plasma CVD. That portions of the interlayer dielectricfilm II which are positioned on the electrodes E1 are used as dielectriclayers of the capacitors C.

On the interlayer dielectric film II, source electrodes SE and drainelectrodes DE shown in FIGS. 2 and 3, video signal lines DL and powersupply lines PSL shown in FIGS. 1 and 3, and electrodes E2 shown in FIG.3 are arranged. These components can be formed in the same step, andhave, e.g., a three-layered structure including Mo/Al/Mo.

The source electrodes SE and drain electrodes DE are electricallyconnected to the sources and drains, respectively, of the TFTs viacontact holes formed in the interlayer dielectric film II.

As shown in FIGS. 1 and 3, the video signal lines DL run in the Ydirection, and are arranged in the X direction. The video signal linesDL are connected to a video signal line driver XDR.

In this embodiment, as shown in FIG. 3, the power supply lines PSL runin the Y direction, and are arranged in the X direction.

The electrodes E2 are connected to the power supply lines PSL. Eachelectrode E2 is used as the other electrode of the capacitor C.

The source electrodes SE, drain electrodes DE, video signal lines DL,power supply lines PSL, and electrodes E2 are covered with a passivationfilm PS shown in FIG. 2. The passivation film PS is made of, e.g.,SiN_(x).

On the passivation film PS, as shown in FIG. 2, light-transmitting firstelectrodes PE as front electrodes are arranged away from each other.Each first electrode PE is a pixel electrode and, as shown in FIGS. 2and 3, connected to the drain electrode DE of the switch SW1 via athrough-hole formed in the passivation film PS.

In this embodiment, the first electrodes PE are anodes. As the materialof the first electrodes PE, it is possible to use, e.g., a transparentconductive oxide such as indium tin oxide (ITO).

A partition insulating layer PI shown in FIG. 2 is further formed on thepassivation film PS. In the partition insulating layer PI, through-holesare formed at positions corresponding to the first electrodes PE, orslits are formed at positions corresponding to the columns or rowsformed by the first electrodes PE. In this embodiment, as an example,through-holes are formed at those positions of the partition insulatinglayer PI which correspond to the first electrodes PE.

The partition insulating layer PI is, e.g., an organic insulating layer.The partition insulating layer PI can be formed by using, e.g.,photolithography.

On each first electrode PE, an organic layer ORG including an emissionlayer is formed. The emission layer is, e.g., a thin film containing aluminescent organic compound which emits red, green, or blue light. Theorganic layer ORG may further include a hole transporting layer, holeinjection layer, hole blocking layer, electron transporting layer, andelectron injection layer, in addition to the emission layer.

The partition insulating layer PI and organic layers ORG are coveredwith a second electrode CE as a back electrode. The second electrode CEis a common electrode connected between the pixels PX, and is alight-reflecting cathode in this embodiment. The second electrode CE is,e.g., electrically connected to electrode interconnections (not shown)formed on the layer on which the video signal lines DL are formed viacontact holes formed in the passivation film PS and partition insulatinglayer PI. Each organic EL element OLED is made up of the first electrodePE, organic layer ORG, and second electrode CE.

Each pixel PX includes the organic EL element OLED and a pixel circuit.In this embodiment, as shown in FIGS. 1 and 3, the pixel circuitincludes the drive control element DR, output control switch SW1, videosignal supply control switch SW2, diode-connecting switch SW3, andcapacitor C. In this embodiment as described above, the drive controlelement DR and the switches SW1 to SW3 are p-channel TFTs. Also, in thisembodiment, the video signal supply control switch SW2 anddiode-connecting switch SW3 form a switch group which switches theconnection state of the drain of the drive control element DR, the videosignal line DL, and the gate of the drive control element DR between afirst state in which they are connected to one another and a secondstate in which they are disconnected from one another.

The drive control element DR, output control switch SW1, and organic ELelement OLED are connected in series in this order between first andsecond power supply terminals ND1 and ND2. In this embodiment, the firstpower supply terminal ND1 is a high-potential power supply terminal, andthe second power supply terminal ND2 is a low-potential power supplyterminal.

The gate of the output control switch SW1 is connected to the scansignal line SL1. The video signal supply control switch SW2 is connectedbetween the video signal line DL and the drain of the drive controlelement DR, and the gate of the video signal supply control switch SW2is connected to the scan signal line SL2. The diode-connecting switchSW3 is connected between the drain and gate of the drive control elementDR, and the gate of the diode-connecting switch SW3 is connected to thescan signal line SL2. The capacitor C is connected between the gate ofthe drive control element DR and a constant-potential terminal ND1′.

To display an image on this organic EL display, the scan signal linesSL1 and SL2, for example, are driven in a line-sequential manner. In awrite period during which a video signal is to be written in a certainpixel PX, the scan signal line driver YDR first outputs a scan signalfor opening the switch SW1 as a voltage signal to the scan signal lineSL1 to which the pixel PX is connected, and outputs a scan signal forclosing the switches SW2 and SW3 as a voltage signal to the scan signalline SL2 to which the pixel PX is connected. In this state, the videosignal line driver XDR outputs a video signal as a current signal to thevideo signal line DL to which the pixel PX is connected, thereby settingthe gate-to-source voltage of the drive control element DR at amagnitude corresponding to the video signal. After that, the scan signalline driver YDR outputs a scan signal for opening the switches SW2 andSW3 as a voltage signal to the scan signal line SL2 to which the pixelPX is connected, and outputs a scan signal for closing the switch SW1 asa voltage signal to the scan signal line SL1 to which the pixel PX isconnected.

In an effective display period during which the switch SW1 is closed, adrive current with a magnitude corresponding to the gate-to-sourcevoltage of the drive control element DR flows through the organic ELelement OLED. The organic EL element OLED emits light at luminancecorresponding to the magnitude of the drive current.

As described previously, a luminous dot with a luminous or darkline-like tail may form in an active matrix display in which a currentsignal is written as a video signal in a pixel circuit. The presentinventor made a thorough examination on the reason of this phenomenon,and has found the following fact.

Assume, for example, that the source and drain of the drive controlelement DR shortcircuit in the pixel PX connected to the scan signallines SL1 and SL2 on the Mth row and to the video signal line DL in theNth column. In this case, the organic EL element OLED of the pixel PXalways emits light at maximum luminance during the effective displayperiod. Therefore, the pixel PX is viewed as a luminous dot.

Also, in this case, in the write period of the pixel PX, the videosignal line driver XDR sets the video signal line DL in the Nth columnat an electric potential substantially equal to that of the first powersupply terminal ND1. That is, the electric potential of the video signalline DL in the Nth column rises excessively. Since the line capacitanceof the video signal line DL is not negligibly small, write periods for,e.g., a few ten rows is necessary before the electric potential of thevideo signal line DL in the Nth row returns to an appropriate range.

Accordingly, of the pixels PX connected to the video signal line DL inthe Nth column, signals smaller than the output from the video signalline driver XDR are written in a few ten pixels from the (M+1)th row. Asa consequence, the luminance of each of these pixels PX becomes lowerthan the intended luminance. Therefore, these pixels PX are viewed as adark line.

For the reason as described above, if the source and drain of the drivecontrol element DR shortcircuit, a luminous dot with a dark line-liketail forms. Note that as is apparent from the above explanation, theluminance of the dark line is not constant, but normally rises from theend on the luminous dot side to the other end.

A luminous dot with a luminous line-like tail forms when, for example,the source and drain of the output control switch SW1 shortcircuit inthe pixel PX connected to the scan signal lines SL1 and SL2 on the Mthrow and to the video signal line DL in the Nth column.

That is, in this case, in the write period of the pixel PX, the videosignal line driver XDR sets the video signal line DL in the Nth columnat an electric potential lower than that of the second power supplyterminal ND2. In the pixel PX, therefore, the gate potential of thedrive control element DR falls extremely. Accordingly, the organic ELelement OLED of the pixel PX always emits light at maximum luminance inthe effective display period. As a consequence, the pixel PX is viewedas a luminous dot.

Also, in this case, in the write period of the pixel PX, the videosignal line DL in the Nth column is set at an excessively low electricpotential. Since the line capacitance of the video signal line DL is notnegligibly small, a write period for, e.g., a few ten rows is necessarybefore the electric potential of the video signal line DL in the Nth rowreturns to an appropriate range.

Accordingly, of the pixels PX connected to the video signal line DL inthe Nth column, signals larger than the output from the video signalline driver XDR are written in a few ten pixels from the (M+1)th row. Asa consequence, the luminance of each of these pixels PX becomes higherthan the intended luminance. Therefore, these pixels PX are viewed as aluminous line.

For the reason as described above, if the source and drain of the outputcontrol switch SW1 shortcircuit, a luminous dot with a luminousline-like tail forms. Note that as is evident from the aboveexplanation, the luminance of the luminous line is not constant, butnormally decreases from the end on the luminous dot side to the otherend.

From the above fact, the present inventor has found that the appearanceof a luminous dot with a luminous or dark line-like tail in an image canbe prevented by the use of the following method.

That is, the structure shown in FIGS. 1 and 2 is formed first by theconventional method. Then, a repair process is performed.

In this repair process, a pixel which may be viewed as a luminous dotwith a luminous or dark line-like tail is first selected from the pixelsPX. Note that the pixel selected herein is a pixel PX corresponding to aluminous dot and is not a pixel PX corresponding to a luminous line ordark line. Note also that the luminous dot noted herein is exclusively adot having a tail in the Y direction.

Then, in the selected pixel PX, both a first conductive path connectingthe first electrode CE of the organic EL element OLED to the first powersupply terminal ND1 and a second conductive path connecting the firstconductive path to the video signal line DL are broken. The firstconductive path is broken at, e.g., a portion which connects the outputcontrol switch SW1 and the first electrode PE of the organic EL elementOLED. Also, the second conductive path is broken at, e.g., a portionwhich connects the video signal supply control switch SW2 and videosignal line DL. Also, the first and second conductive paths are brokenby irradiating the semiconductor layers SC of these paths with a laserbeam.

When the first conductive path is broken in the selected pixel PX, theorganic EL element OLED included in the pixel PX does not emit light inthe effective display period. Therefore, the pixel PX is not viewed as aluminous dot.

Also, when the second conductive path is broken in the selected pixelPX, the electric potential of the video signal line DL to which thepixel PX is connected is not affected by the electric potential of thefirst or second power supply terminal ND1 or ND2 in the write period ofthe pixel PX. Accordingly, no luminous line or dark line is produced bythe influence of the pixel PX.

When the repair described previously is performed, therefore, it ispossible to prevent the appearance of a luminous dot with a luminous ordark line-like tail in an image.

This repair leaves traces explained below in the pixel PX. These traceswill be described with reference to FIG. 4.

FIG. 4 is a plan view schematically showing a structure after the pixelshown in FIG. 3 is repaired.

In this embodiment as described above, a pixel PX which may be viewed asa luminous dot with a luminous or dark line-like tail is selected, andboth the first and second conductive paths are broken in the pixel PX.Therefore, in the completed organic EL display, some pixels PX includetwo broken portions.

For example, the structure shown in FIG. 4 is obtained when the firstconductive path is broken at a portion which connects the output controlswitch SW1 and the first electrode PE of the organic EL element OLED,and the second conductive path is broken at a portion which connects thevideo signal supply control switch SW2 and video signal line DL. Notethat when the semiconductor layer SC is crystalline like polysilicon andeach path is to be broken at the position of the semiconductor layer SC,a phase change from crystalline to amorphous can be produced byirradiating the semiconductor layer SC with a laser beam. In this case,even if the semiconductor layer SC is physically incompletely broken byirradiation with the laser beam, its electric resistance risessignificantly, so the electrical disconnection cannot be insufficient.

Although the organic EL display using the arrangement shown in FIG. 1 asthe pixel PX is explained above, another arrangement may be used as thepixel PX. For example, it is possible to connect the video signal supplycontrol switch SW2 and diode-connecting switch SW3 in series in thisorder between the video signal line DL and the drain of the drivecontrol element DR, and connect the drain of the diode-connecting switchSW3 to the gate of the drive control element DR. Alternatively, thediode-connecting switch SW3 may be connected not between the drain andgate of the drive control element DR, but between the gate of the drivecontrol element DR and the video signal line DL. Alternatively, theswitch group may be made up of three or more switches, instead of thetwo switches, i.e., the video signal supply control switch SW2 anddiode-connecting switch SW3.

FIG. 5 is an equivalent circuit diagram of a pixel included in a displayaccording to a modification. FIG. 6 is a plan view schematically showingan example of a structure usable as the pixel of the display accordingto the modification. Note that FIG. 6 illustrates the structure of thepixel viewed from the display surface side.

A pixel PX shown in FIGS. 5 and 6 has the same structure as the pixel PXshown in FIGS. 1 and 3 except that not a video signal supply controlswitch SW2 but video signal supply control switches SW2 a and SW2 b areconnected in series in this order between a video signal line DL and thedrain of a drive control element DR. That is, a switch group is made upof the video signal supply control switches SW2 a and SW2 b and adiode-connecting switch SW3, instead of the video signal supply controlswitch SW2 and diode-connecting switch SW3. In this way, the switchgroup may be made up of three or more switches.

When the structure shown in FIGS. 5 and 6 is used as the pixel PX, therepair described above may be performed in the following manner. Thisrepair will be explained below with reference to FIGS. 7 and 8.

FIG. 7 is a plan view schematically showing an example of a structureafter the pixel shown in FIG. 6 is repaired. FIG. 8 is a plan viewschematically showing another example of the structure after the pixelshown in FIG. 6 is repaired.

Even when the structure shown in FIGS. 5 and 6 is used as the pixel PX,a pixel PX which may be viewed as a luminous dot with a luminous or darkline-like tail is selected in the same manner as above. Then, both firstand second conductive paths are broken in the pixel PX.

The second conductive path can be broken at, e.g., a portion connectingthe video signal supply control switch SW2 a and video signal line DL.In this case, if the first conductive path is broken at a portionconnecting an output control switch SW1 and a first electrode PE of anorganic EL element OLED, the structure shown in FIG. 7 is obtained.

The second conductive path may be broken at a portion connecting thevideo signal supply control switches SW2 a and SW2 b. In this case, ifthe first conductive path is broken at the portion connecting the outputcontrol switch SW1 and the first electrode PE of the organic EL elementOLED, the structure shown in FIG. 8 is obtained.

The organic EL display described above uses an arrangement in which thefirst and second conductive paths do not overlap any otherinterconnections or electrodes in their broken portions when viewed in adirection perpendicular to the main surface of a substrate SUB. Thismakes it possible to protect the other interconnections or electrodesfrom being damaged by laser beam irradiation for breaking the first andsecond conductive paths. Especially when the distance between the brokenportions and the interconnections or electrodes other than the first andsecond conductive paths is about 2 μm or more when viewed in thedirection perpendicular to the main surface of the substrate SUB, it isreadily possible to protect the other interconnections or electrodesfrom being damaged by laser beam irradiation for breaking the first andsecond conductive paths.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An organic EL display comprising an insulating substrate, pixelsarranged in a matrix form on the insulating substrate, and video signallines arranged correspondently with columns which the pixels form,wherein each of the pixels comprises: a drive control element whichincludes a control terminal, a first terminal connected to a first powersupply terminal, and a second terminal outputting a current with amagnitude corresponding to a voltage between the control terminal andthe first terminal; an organic EL element which includes a firstelectrode, a second electrode connected to a second power supplyterminal, and an active layer interposed between the first and secondelectrodes; an output control switch which is connected between thesecond terminal and the first electrode; a switch group which switchesan electrical connection between first and second states, the firststate being a state that the second terminal, the video signal line, andthe control terminal are electrically connected to one another, and thesecond state being a state that the second terminal, the video signalline, and the control terminal are electrically disconnected from oneanother; and a capacitor which is connected to the control terminal,wherein a first conductive path electrically connecting the firstelectrode to the first power supply terminal and a second conductivepath electrically connecting the second terminal to the video signalline are broken in a part of the pixels.
 2. The display according toclaim 1, wherein the switch group includes a video signal supply controlswitch connected to the video signal line, and a diode-connecting switchconnected to the control terminal, and wherein, in the pixel in whichthe first and second conductive paths are broken, a part of the secondconductive path connecting the video signal supply control switch to thevideo signal line is broken, and a part of the first conductive pathconnecting the output control switch to the first electrode is broken.3. The display according to claim 1, wherein the switch group includesvideo signal supply control switches connected in series to the videosignal line, and a diode-connecting switch connected to the controlterminal, and wherein, in the pixel in which the first and secondconductive paths are broken, a part of the second conductive pathconnecting one of the video signal supply control switches to the videosignal line is broken, and a part of the first conductive pathconnecting the output control switch to the first electrode is broken.4. The display according to claim 1, wherein the switch group includesvideo signal supply control switches connected in series to the videosignal line, and a diode-connecting switch connected to the controlterminal, and wherein, in the pixel in which the first and secondconductive paths are broken, a part of the second conductive pathconnecting the video signal supply control switches to each other isbroken, and a part of the first conductive path connecting the outputcontrol switch to the first electrode is broken.
 5. The displayaccording to claim 1, wherein the first and second conductive pathsinclude first and second polysilicon portions, respectively, andwherein, in the pixel in which the first and second conductive paths arebroken, the first and second polysilicon portions are broken.
 6. Anorganic EL display comprising: plural pixels, each of the pixelscomprising, a drive control element which includes a control terminal, afirst terminal connected to a first power supply terminal, and a secondterminal outputting a current with a magnitude corresponding to avoltage between the control terminal and the first terminal, an organicEL element which includes a first electrode, a second electrodeconnected to a second power supply terminal, and an active layerinterposed between the first and second electrodes, and an outputcontrol switch which is connected between the second terminal and thefirst electrode, wherein in a part of the pixels, a first conductivepath electrically connecting the first electrode to the first powersupply terminal is broken at a portion which connects the output controlswitch to the first electrode.
 7. The display according to claim 6,further comprising video signal lines to which the pixels areelectrically connected, wherein each of the pixels further comprises aswitch group which switches an electrical connection between first andsecond states, the first state being a state that the second terminal,the video signal line, and the control terminal are electricallyconnected to one another, and the second state being a state that thesecond terminal, the video signal line, and the control terminal areelectrically disconnected from one another, and wherein in the pixel inwhich the first conductive path is broken, a second conductive pathelectrically connecting the second terminal to the video signal line isfurther broken.
 8. The display according to claim 7, wherein the switchgroup includes a video signal supply control switch connected to thevideo signal line, and a diode-connecting switch connected to thecontrol terminal, and wherein in the pixel in which the first and secondconductive paths are broken, a part of the second conductive pathconnecting the video signal supply control switch to the video signalline is broken.
 9. The display according to claim 7, wherein the switchgroup includes video signal supply control switches connected in seriesto the video signal line, and a diode-connecting switch connected to thecontrol terminal, and wherein in the pixel in which the first and secondconductive paths are broken, a part of the first conductive pathconnecting one of the video signal supply control switches to the videosignal line is broken, and a part of the second conductive pathconnecting the output control switch to the first electrode is broken.10. The display according to claim 7, wherein the switch group includesvideo signal supply control switches connected in series to the videosignal line, and a diode-connecting switch connected to the controlterminal, and wherein in the pixel in which the first and secondconductive paths are broken, a part of the first conductive pathconnecting the video signal supply control switches to each other isbroken, and a part of the second conductive path connecting the outputcontrol switch to the first electrode is broken.
 11. The displayaccording to claim 7, wherein the first and second conductive pathsinclude first and second polysilicon portions, respectively, and whereinin the pixel in which the first and second conductive paths are broken,the first and second polysilicon portions are broken.
 12. An organic ELdisplay comprising: an insulating substrate; video signal lines eachextending in a first direction above the insulating substrate; powersupply lines each extending in the first direction above the insulatingsubstrate, the power supply lines and the video signal lines beingarranges in a second direction crossing the first direction; first scansignal lines each extending in the second direction above the insulatingsubstrate and arranged in the first direction; and pixels arranged abovethe insulating substrate and each including a drive control elementincluding a control terminal, a first terminal and a second terminal,the first terminal being connected to the power supply line, the secondterminal outputting a current with a magnitude corresponding to avoltage between the control terminal and the first terminal, an organicEL element including a first electrode, a second electrode and an activelayer, the second electrode being connected to a power supply terminal,the active layer being interposed between the first and secondelectrodes, and a first transistor connected between the second terminaland the first electrode, the first transistor including a part of thefirst scan signal line as a gate, wherein in a part of the pixels, afirst conductive path electrically connecting the first electrode to thepower supply line is broken at a portion which connects the firsttransistor to the first electrode.
 13. The display according to claim12, further comprising second scan signal lines each extending in thesecond direction above the insulating substrate and arranged in thefirst direction, each of the second scan signal lines including aprotruding portion protruding in the first direction, wherein each ofthe pixels further includes a second transistor connected to the videosignal line and having the protruding portion as a gate.
 14. The displayaccording to claim 12, wherein the first conductive path includes afirst polysilicon portion extending in the first direction, and whereinin the pixel in which the first conductive path is broken, a part of thefirst polysilicon portion is broken.
 15. The display according to claim14, further comprising second scan signal lines each extending above theinsulating substrate in the second direction and arranged in the firstdirection, each of the second scan signal lines intersecting the firstpolysilicon portion, wherein each of the pixels further includes a thirdtransistor connected to the control terminal, the third transistorincluding parts of the second scan signal line and the first polysiliconportion facing each other.
 16. The display according to claim 12,wherein each of the pixels further includes a capacitor having third andfourth electrodes facing each other, and wherein the drive controlelement includes a transistor having a portion of the third electrode asa gate.
 17. The display according to claim 12, wherein the drive controlelement includes a transistor having a second polysilicon portion, thesecond polysilicon portion extending in the second direction.
 18. Anorganic EL display comprising: an insulating substrate; video signallines each extending in a first direction above the insulatingsubstrate; power supply lines each extending in the first directionabove the insulating substrate, the power supply lines and the videosignal lines being arranged in a second direction crossing the firstdirection; first scan signal lines each extending in the seconddirection above the insulating substrate and arranged in the firstdirection; and pixels arranged above the insulating substrate and eachincluding, an organic EL element including a first electrode, a secondelectrode and an active layer, the active layer being interposed betweenthe first and second electrodes, a capacitor including third and fourthelectrodes facing each other, a first polysilicon portion including afirst part, a second part, and a third part between the first and secondparts, the first polysilicon portion intersecting the first scan signalline at the third part and being electrically connected to the firstelectrode at the first part, and a second polysilicon portion includinga fourth part, a fifth part, and a sixth part between the fourth andfifth parts, the second polysilicon portion intersecting the thirdelectrode at the sixth part and being electrically connected to thepower supply line and the second part at the fourth and fifth parts,respectively, wherein in a part of the pixels, a first polysiliconportion is broken at the first part.
 19. The display according to claim18, further comprising second scan signal lines each extending in thesecond direction above the insulating substrate and arranged in thefirst direction, each of the second scan signal lines including aprotruding portion protruding in the first direction, wherein the firstpolysilicon portion further includes a seventy part and an eighth partbetween the second and seventh parts, the first polysilicon portionbeing electrically connected to the video signal line at the seventhpart and intersecting the protruding portion at the eighth part.
 20. Thedisplay according to claim 19, wherein in the pixel in which the firstpolysilicon portion is broken at the first part, the first polysiliconportion is further broken at the seventh part.
 21. The display accordingto claim 18, further comprising second scan signal lines each extendingin the second direction above the insulating substrate and arranged inthe first direction, wherein the first polysilicon portion furtherincludes a ninth part and a tenth part between the second and ninthparts, the first polysilicon portion being electrically connected to thefourth electrode at the ninth part and intersecting the second scansignal line at the tenth part.